On-bonder automatic overhang die optimization tool for wire bonding and related methods

ABSTRACT

A method of providing a z-axis force profile applied to a plurality of bonding locations during a wire bonding operation is provided. The method includes: (a) determining a z-axis force profile for each of a plurality of bonding locations on an unsupported portion of at least one reference semiconductor device; and (b) applying the z-axis force profile during subsequent bonding of a subject semiconductor device. Methods of: determining a maximum bond force applied to a bonding location during formation of a wire bond; and determining a z-axis constant velocity profile for formation of a wire bond, are also provided.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit of U.S. Provisional Application62/250,745, filed Nov. 4, 2015, and of U.S. Non-Provisional patentapplication Ser. No. 15/234,563 the contents of both of which areincorporated herein by reference.

FIELD

The invention relates to the wire bonding operations, and moreparticularly, to improved methods of determining wire bond programparameters for use in connection with overhang die applications.

BACKGROUND

In the semiconductor packaging industry, wire bonding continues to aprimary method of providing electrical interconnection between two (ormore) locations within a package. In a typical wire bonding application,a wire bonding tool (e.g., a capillary bonding tool in a ball bondingapplication, a wedge bonding tool in a wedge bonding application, etc.)is used to bond a first end of wire to a first bonding location to forma first bond. Then, a length of wire continuous with the first bond isextended toward a second bonding location. Then, a second bond(continuous with the first bond and the length of wire) is formed at thesecond bonding location. Thus, a wire loop is formed between the firstbonding location and the second bonding location. During formation ofwire bonds various types of energy (e.g., ultrasonic, thermosonic,thermocompressive, etc.) may be used, in connection with bond forceand/or heat.

In certain types of semiconductor packages, various semiconductor diesare arranged in a “stacked die” configuration. In such packages, one ormore of the dies may overhang other dies (or spacers, substrates, etc.).FIG. 1 illustrates such a package. In FIG. 1, a lower semiconductor die102 is supported by a substrate 100 (where a wire loop 108 providesinterconnection between a bonding location on die 102 and anotherbonding location on substrate 100). A spacer 104 is positioned betweenlower semiconductor die 102 and an upper semiconductor die 106. Uppersemiconductor die 106 includes an unsupported portion that hangs overspacer 104 and lower semiconductor die 102. As such, upper semiconductordie 106 may be termed an “overhang die”.

In FIG. 1, it is desirable to form another wire loop between uppersemiconductor die 106 and another location (e.g., substrate 100). FIG. 1illustrates the beginning of the bonding process, as a ball bond 112 isbeing bonded (as a first bond) to a bonding location on uppersemiconductor die 106 using a wire bonding tool 110 (where wire bondingtool 110 is carried by a bond head assembly 114). Because uppersemiconductor die 106 is an overhang die, the die bends (i.e., diedeflection, as shown in FIG. 1). This die deflection can result indamage to the overhang die itself (e.g., cracking, etc.) or damagethrough contact with other structures below the overhang die (e.g., suchas wire loop 108).

Thus, it would be desirable to provide improved methods of controllingpotential damage in connection with wire bonding in overhang dieapplications.

SUMMARY

According to an exemplary embodiment of the invention, a method ofproviding a z-axis force profile applied to a plurality of bondinglocations during a wire bonding operation is provided. The methodincludes: (a) determining a z-axis force profile for each of a pluralityof bonding locations on an unsupported portion of at least one referencesemiconductor device; and (b) applying the z-axis force profile duringsubsequent bonding of a subject semiconductor device.

According to another exemplary embodiment of the invention, a method ofdetermining a maximum bond force to be applied to a bonding locationduring formation of a wire bond is provided. The method includes: (a)providing a maximum z-axis deflection value for at least one referencesemiconductor device; (b) measuring z-axis deflection values at aplurality of bonding locations on at least one reference semiconductordevice at a plurality of bond force values; and (c) determining themaximum bond force for each of the bonding locations.

According to yet another exemplary embodiment of the invention, a methodof determining a z-axis constant velocity profile for formation of awire bond is provided. The method includes: (a) providing a maximumz-axis deflection value for a semiconductor device; (b) measuring z-axisdeflection values at a plurality of bonding locations on at least onereference semiconductor device at a plurality of z-axis constantvelocity profiles; and (c) determining a z-axis constant velocityprofile for each of the bonding locations.

According to yet another exemplary embodiment of the invention, a methodof determining a maximum bonded ball diameter is provided. The methodincludes: (a) determining a maximum bond force for a bonding locationfor the formation of wire bonds; (b) determining a z-axis constantvelocity profile for formation of wire bonds at the bonding location;and (c) determining, on a computer, a maximum bonded ball size for thebonding location using the maximum bond force determined in step (a) andthe z-axis constant velocity profile in step (b).

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is best understood from the following detailed descriptionwhen read in connection with the accompanying drawings. It is emphasizedthat, according to common practice, the various features of the drawingsare not to scale. On the contrary, the dimensions of the variousfeatures are arbitrarily expanded or reduced for clarity. Included inthe drawings are the following figures:

FIG. 1 is a block diagram side view of a portion of a conventionalstacked die device including an overhang die;

FIG. 2 is a timing diagram illustrating a z-axis position profile of aportion of a bond head assembly of a wire bonding machine duringformation of first bond of a wire loop useful in illustrating variousexemplary embodiments of the invention;

FIG. 3 is a timing diagram illustrating a z-axis position profile of aportion of a bond head assembly of a wire bonding machine duringformation of first bond of a wire loop in accordance with an exemplaryembodiment of the invention;

FIG. 4 is a force profile illustrating a force applied by a bonding toolof a wire bonding machine during formation of a wire bond useful inillustrating various exemplary embodiments of the invention;

FIG. 5A is a simplified overhead block diagram view of an overhang dieincluding three bonding locations useful in illustrating variousexemplary embodiments of the invention;

FIG. 5B is a timing diagram illustrating a z-axis position of a portionof a bond head assembly of a wire bonding machine during formation ofwire bonds at various locations of the overhang die of FIG. 5A inaccordance with an exemplary embodiment of the invention;

FIG. 5C is a bond force profile illustrating a bond force applied by awire bonding tool of a wire bonding machine during formation of wirebonds at various locations of the overhang die of FIG. 5A in accordancewith an exemplary embodiment of the invention;

FIG. 6 is a flow diagram illustrating a method of providing a z-axisforce profile applied to a plurality of bonding locations during a wirebonding operation in accordance with an exemplary embodiment of theinvention;

FIG. 7 is a flow diagram illustrating a method of determining a maximumbond force to be applied to a bonding location during formation of awire bond in accordance with an exemplary embodiment of the invention;

FIG. 8 is a flow diagram illustrating a method of determining a z-axisconstant velocity profile for formation of a wire bond in accordancewith an exemplary embodiment of the invention; and

FIG. 9 is a flow diagram illustrating a method of determining a maximumbonded ball diameter in accordance with an exemplary embodiment of theinvention.

DETAILED DESCRIPTION

As used herein, the term “z-axis force profile” refers to a force to beapplied in connection with a wire bonding operation (or a portion of awire bonding operation) along a z-axis during a time period. Such aprofile may be provided in a number of formats including but not limitedto, for example, a graphical format (e.g., see FIG. 4), a tabular format(e.g., a series of force values at increments of time), etc. Such aforce profile may be provided for an entire bonding cycle (such as thegraph in FIG. 4), or may be provided for part of a bonding cycle (e.g.,during the force ramp down, leading to lift off, corresponding to thedotted line portion of FIG. 3).

In accordance with certain exemplary embodiments of the invention,system and methods that automatically determine (e.g., compute) wirebonding parameters such as optimal damping gain (e.g., a force profileduring force ramp down after bonding related to the wire bonding toolcoming off the die in a predictable manner), maximum die settle time,maximum safe contact velocity (e.g., in a constant velocity mode), andmaximum safe bond force are provided for an overhang (overhanging)semiconductor device on a wire bonder (i.e., a wire bonding machine).Such parameters may be provided specific to each bonding location on theoverhang semiconductor device (e.g., an overhang semiconductor die).

When a wire bonding tool (carried by a bond head assembly of a wirebonding machine) makes contact with a bond pad (or other bondinglocation) on an unsupported portion of an overhang die (or anotheroverhang semiconductor device), the die surface deflects downwards. Thisdeflection may cause a number of issues with wire bonding and loopshaping, for example, due to die vibration when the wire bonding toollifts off of the die surface after bonding. Characterizing andoptimizing a wire bond process for an overhang die is thereforeextremely difficult and tedious. Certain aspects of the invention relateto automatically performing an in situ characterization and optimizationof an overhang die on a wire bonder. For example, using a z-axis encoderfeedback and an iterative method, the key overhang devicecharacteristics may be quantified such as optimal damping gain, maximumdie settle time, maximum safe contact velocity and maximum safe bondforce for all programmed locations on an overhang die.

In accordance with certain exemplary embodiments of the invention, abond program is taught with programmed bonding locations on an overhangdie. A bonding tool (e.g., a capillary) touches down repeatedly (e.g.,with or without wire engaged in the bonding tool) on each programmedbonding location with pre-defined starting values of certain parameterssuch as damping gain, contact velocity (e.g., in a constant velocitymode) and bond force. The z-axis encoder data is used to provide datawhich is then collected and analyzed. The data may be compared with userdefined values (e.g., allowable die deflection, desired bond force,etc.) to determine the maximum die deflection and maximum safe bondforce. In the subsequent iterations, the maximum safe contact velocity(i.e., in a constant velocity mode), optimal damping gain, and maximumdie settle time may be determined. Such a process may be repeatedautomatically until convergence to a desired die deflection is achievedfor all programmed locations (e.g., on a reference semiconductordevice), typically in 6-10 iterations per programmed location. Theresults are displayed and saved to the bond program (e.g., for eachprogrammed bonding location of a die) from where they can be usedautomatically during live wire bonding (e.g., on subject semiconductordevices).

Using these inventive techniques, feedback (e.g., instantaneous or realtime feedback) may be provided to the wire bonder and user on theoverhang device characterization. Thus, optimized key bonding parameterssuch as damping gain, maximum die settle time, contact velocity and bondforce may automatically be determined for each bonding location on anoverhang die.

In determining the optimal damping gain for each bonding location, theprocess should generate a force profile (e.g., a profile of bond forceversus time during force ramp down after bonding, a profile of bondforce versus time during initial contact before bonding, etc.) thatreduces potential oscillation, but also maintains a minimal die settletime such that the UPH (i.e., units per hour) processed during the wirebonding process is not adversely affected.

In determining (1) a maximum bond force during bonding, and/or (2) az-axis constant velocity profile for formation of a wire bond, a user ofthe wire bonding machine may enter a maximum deflection of the overhangdie (e.g., where the entered maximum deflection does not result inproblems such as the overhang die striking a wire loop beneath theoverhang die, where the maximum deflection does not result in damage tothe die such as die cracking, etc.). In another example, the wirebonding machine may automatically determine the maximum deflection ofthe overhang die (e.g., a maximum deflection value that does not resultin damage to the die such as die cracking, as determined by the wirebonding machine). During an iterative process, the wire bonder measuresthe z-axis position (e.g., using the z-axis encoder of the bond head ofthe wire bonding machine) and provides z-axis position data related toapplied bond force and a constant velocity (CV) profile. Using thisdata, the maximum bond force, and the maximum CV profile may bedetermined.

FIG. 2 illustrates a z-axis position of the bond head assembly (wherethe bond head assembly carries the wire bonding tool) of a wire bondingmachine during formation of a wire bond (e.g., a first bond of a wireloop, such as a ball bond formed with a free air ball). As will beappreciated by those skilled in the art, the z-axis of a wire bondingmachine is a vertical axis (or a substantially vertical axis) alongwhich a wire bonding tool travels. The z-axis position may be detectedusing a z-axis encoder of the wire bonding machine or another technique.As shown in FIG. 2, the wire bonding tool descends along the z-axis in aconstant velocity mode (“CONSTANT VELOCITY” in FIG. 2). During thisdescent there is contact with the die (“CONTACT WITH DIE” in FIG. 2).The descent continues after contact with the die, because of theoverhang nature of the die. Then contact with the die is declared(“CONTACT WITH DIE DECLARED” in FIG. 2), and the “BONDING” processbegins. After the bonding process is completed, the wire bonding tool israised, along with a force ramp down from bond force to a reduced levelof force (e.g., shown as “Z-AXIS LIFT OFF” in FIG. 2) after the “END OFBONDING”. For example, 20 grams of bond force may be applied duringbonding, but a reduced force might be 2 grams. In terms of time, itwould be desirable to accomplish the force ramp down as soon aspossible; however, because of the overhang nature of the die, dieoscillation results as shown in FIG. 2. After a period of time, the diesettles (the oscillation stops, see “DIE SETTLED” in FIG. 2) and the dieis at the equilibrium position. A problem is that the die oscillationmay cause damage to the overhang die (e.g., cracking), damage to wireloops bonded to the overhang die, damage to wire loops below theoverhang die, etc.

FIG. 3 is substantially similar to FIG. 2, except that in FIG. 3, asecond curve is shown (the dotted line curve) where the force ramp downhas been adjusted (e.g., a desirable z-axis force profile has beenapplied) such that the die oscillation has been substantially reduced.That is, instead of a quick removal of the bond force (e.g., from 20grams to 2 grams as in the example described above), a z-axis forceprofile is applied particular to the bonding location. For example, amore gradual reduction of bond force might be utilized during the forceramp down phase (after “END OF BONDING”), as shown in the dotted lineportion of the curve in FIG. 3, as compared to the solid curve. Thisforce profile should be balanced such that an excessive time is notused, reducing UPH (units per hour).

FIG. 4 illustrates an example bond force profile during bonding (bondingof a free air ball as a first bond of a wire loop, or as a bump) of anoverhang die. This bond force profile, or any portion of this bond forceprofile, may be termed a z-axis force profile. Such a bond force profilegives rise to a z-axis position profile (such as the examples shown inFIGS. 2-3). The bond force profile of FIG. 4 begins at a zero value bondforce (no contact, shown as “ZERO BOND FORCE” in FIG. 4) and increasesupon contact, and reaches a peak impact force in CV (constant velocity)mode. After deformation of the free air ball, the force is reducedsomewhat to a “BOND FORCE” which is applied as a substantially uniformbond force during the “BOND TIME” in FIG. 4. Then the “TIME TO LIFT OFF”occurs during which the force is ramped down from the “BOND FORCE” to a“LIFT OFF FORCE”. The force remains at this low level of force such thatthe overhang die can settle. Then the force is reduced to the zero bondforce level. In accordance with certain exemplary embodiments of theinvention, a z-axis force profile is generated for each bonding locationduring the “TIME TO LIFT OFF” period shown in FIG. 4 (and/or duringinitial contact during the “PEAK IMPACT FORCE DURING CV MODE” phaseshown in FIG. 4, and/or during other portions of a wire bondingoperation), for example, to reduce oscillation as shown in the dottedline in FIG. 3.

In accordance with certain exemplary embodiments of the invention, eachbonding location may be considered independently, and a z-axis forceprofile is generated for that unique bonding location (e.g., including aforce ramp down profile after bonding, or a force profile during initialimpact, etc.). FIG. 5A illustrates a simple overhang die positionedabove a bottom die/spacer having a smaller footprint compared to theoverhang die. The overhang die includes three bonding locations (i.e.,“a”, “b”, and “c”). As shown in FIG. 5A, locations “a” and “c” are adistance 1.4× from the bottom die, while location “b” is a smallerdistance “x” from the bottom die. Thus, the overhang die would tend tobe stiffer at location “b”, and would deflect more under a uniform forceapplication at locations “a” and “c”. It is often desirable to apply aconsistent level of amount of bond force and CV for all bondinglocations during the actual bonding. Thus, as shown in the z-axisposition profile in FIG. 5B (similar to the z-axis position profile ofFIG. 3), the z-axis position during “BONDING” is lower for locations “a”and “c” because the same bond force is applied to bonding locations “a”and “c” as compared to location “b”. That z-axis position profile forbonding locations “a” and “c” is shown in dotted lines in FIG. 5B (anyunacceptable level of die oscillation is not shown in FIG. 5B forsimplicity). But such a lower z-axis position for bonding locations “a”and “c” may involve an unacceptable level of die deflection. Thus, bondforce ramp down (the force after bonding associated with lift off) maybe changed for bonding locations “a” and “c”. FIG. 5C illustrates thebond force profiles (which are analogous to the z-axis force profileshown in FIG. 4) for location “b”, and for locations “a” and “c”. Asshown in FIG. 5C, the force ramp down for locations “a” and “c” is muchmore gradual compared to location “b”. This force ramp down, which isspecific to each bonding location, allows for a reduction in potentialoscillation.

FIGS. 5A-5C are also instructive for the automatic determination of a(1) a maximum bond force during bonding, and/or (2) a z-axis constantvelocity profile for formation of a wire bond, in accordance withexemplary embodiments of the invention. That is, because the differentbonding locations “a”, “b”, and “c” deflect differently, an acceptablemaximum bond force may be different for each location. Using the userprovided maximum deflection value, an iterative approach is used tomeasure deflection at each bonding location at different levels of bondforce. An acceptable maximum bond force may then be determined that maybe used for all of the bonding locations. The same approach may be takento determine an acceptable z-axis constant velocity profile that may beused for all bonding locations, without exceeding the user providedmaximum deflection value.

FIGS. 6-9 are flow diagrams in accordance with certain exemplaryembodiments of the invention. As is understood by those skilled in theart, certain steps included in the flow diagrams may be omitted; certainadditional steps may be added; and the order of the steps may be alteredfrom the order illustrated.

FIG. 6 is a flow diagram illustrating a method of providing a z-axisforce profile (such as a the force profile shown in FIG. 4 or FIG. 5C)applied to a plurality of bonding locations during a wire bondingoperation. At Step 600, a z-axis oscillation is measured at each of theplurality of bonding locations on an unsupported portion of at least onereference semiconductor device. For example, the z-axis oscillation maybe measured (e.g., using a z-axis encoder of a bond head of a wirebonding machine) at each of the plurality of bonding locations at aplurality of z-axis force values in connection with the determination ofthe z-axis force profile for each of the plurality of bonding locations.In a specific example, the z-axis oscillation may be measured inconnection with an iterative process such that the z-axis force profileis determined for each of the bonding locations that will result in adesirable z-axis deflection profile for each bonding location (e.g.,such that a maximum deflection value included in the z-axis deflectionprofile is below a predetermined threshold). At Step 602, a z-axis forceprofile is determined for each of the plurality of bonding locationsusing the z-axis oscillation measurements from Step 600 (e.g., using theiterative process to determine a z-axis force profile resulting in anacceptable z-axis deflection profile, where a maximum deflection valueof the acceptable z-axis deflection profile is below a predeterminedthreshold.). At Step 604, the z-axis force profile determined in Step602 is applied during subsequent bonding of a subject semiconductordevice. That is, Steps 600 and 602 may be performed in connection with areference semiconductor device(s), and may be performed with (orwithout) wire engaged with the wire bonding tool. At Step 604, actualwire bonding is performed in connection with subject semiconductordevices (e.g., devices in production), using the z-axis force profiledetermined in Step 602.

FIG. 7 is a flow diagram illustrating a method of determining a maximumbond force to be applied to a bonding location during formation of awire bond. At Step 700, a maximum z-axis deflection value is providedfor at least one reference semiconductor device. Such a maximum z-axisdeflection value may be provided in a number of methods. In certainexamples, a user of the wire bonding machine may provide the maximumdeflection of the overhang die, for example: the user may identify themaximum deflection through testing and experimentation such that themaximum deflection does not result in problems such as (i) the overhangdie striking a wire loop beneath the overhang die, and/or (ii) damage tothe die such as die cracking. In another example, the wire bondingmachine may automatically determine the maximum deflection of theoverhang die (e.g., a maximum deflection value that does not result indamage to the die such as die cracking, as determined by the wirebonding machine through a process wherein varying levels of diedeflection are tested, for example, using a z-axis encoder, and diecrack can be identified by the machine because the die does not properlyrestore after some amount of deflection). At Step 702, z-axis deflectionvalues are measured at a plurality of bonding locations on at least onereference semiconductor device at a plurality of bond force values. Forexample, such deflection values may be measured using a z-axis encoderof the wire bonding machine. Steps 702 may be performed in connectionwith (or without) wire engaged with the wire bonding tool. At Step 704,the maximum bond force is determined for each of the bonding locations:that is, the maximum deflection value from Step 700, and the z-axisdeflection values measured at Step 702 at multiple bond force values,are used to determine an acceptable maximum bond force value. Step 704may include determining the maximum bond force as a single value thatmay be applied to each of the bonding locations, or may includedetermining the maximum bond force as a plurality of values, each of thebonding locations having a corresponding maximum bond force included inthe plurality of values.

FIG. 8 is a flow diagram illustrating a method of determining a z-axisconstant velocity profile (e.g., which may be a z-axis slope during apredetermined period of time) for formation of a wire bond. At Step 800,a maximum z-axis deflection value for a semiconductor device isprovided. Such a maximum z-axis deflection value may be provided asdescribed above in connection with Step 700 of FIG. 7. At Step 802,z-axis deflection values are measured at a plurality of bondinglocations on at least one reference semiconductor device at a pluralityof z-axis constant velocity profiles. As provided above with respect toStep 702 of FIG. 7, such deflection values may be measured using az-axis encoder of the wire bonding machine. At Step 804, a z-axisconstant velocity profile is determined for each of the bondinglocations: that is, the maximum deflection value from Step 800, and thez-axis deflection values measured at Step 802 at multiple z-axisconstant velocity profiles, are used to determine an acceptable z-axisconstant velocity profile at Step 804. Step 704 may include determiningthe z-axis constant velocity profile as a single profile that may beapplied to each of the bonding locations, or may include determining thez-axis constant velocity profile as a plurality of profiles, each of thebonding locations having a corresponding z-axis constant velocityprofile included in the plurality of profiles.

FIG. 9 is a flow diagram illustrating a method of determining a maximumbonded ball diameter. In certain wire bonding applications, a free airball is bonded to a bonding location to form a bonded ball. The diameterof this bonded ball is an important characteristic of the wire bond, andmay be used as an input to derive bonding parameters for forming a wirebond (See, e.g., U.S. Patent Application Publication No. 2012/0074206).Thus, it may be important to know the maximum bonded ball diameter thatis possible in a given application, including overhang die applications.At Step 900, a maximum bond force applied to a bonding location for theformation of a wire bond is determined. For example, the maximum bondforce may be determined using the method disclosed in FIG. 7. At Step902, a z-axis constant velocity profile for formation of a wire bond atthe bonding location is determined. For example, the z-axis constantvelocity profile may be determined using the method disclosed in FIG. 8.At Step 904, a maximum bonded ball size for the bonding location isdetermined, on a computer, using the maximum bond force determined inStep 900 and the z-axis constant velocity profile in Step 902. Thecomputer may be, for example, a computer on a wire bonding machine, or aseparate computer system. Step 904 may include using at least one datastructure (e.g., look-up tables, databases, etc.) accessible by thecomputer, where the data structure(s) includes values related to amaximum bonded ball size, along with the maximum bond force and thez-axis constant velocity profile. Such a data structure(s) may be usedby the computer to determine the maximum bonded ball size.

Although the invention is illustrated and described herein withreference to specific embodiments, the invention is not intended to belimited to the details shown. Rather, various modifications may be madein the details within the scope and range of equivalents of the claimsand without departing from the invention.

What is claimed:
 1. A method of providing a z-axis force profile appliedto a plurality of bonding locations during a wire bonding operation, themethod comprising the steps of: (a) determining a z-axis force profilespecific to each of a plurality of bonding locations on an unsupportedportion of at least one reference semiconductor device; and (b) applyingthe z-axis force profile during subsequent bonding of a subjectsemiconductor device.
 2. The method of claim 1 wherein step (a) includesmeasuring a z-axis oscillation at each of the plurality of bondinglocations to determine the z-axis force profile for each of theplurality of bonding locations.
 3. The method of claim 2 wherein step(a) further includes measuring the z-axis oscillation at each of theplurality of bonding locations at a plurality of z-axis force values todetermine the z-axis force profile for each of the plurality of bondinglocations.
 4. The method of claim 2 wherein the z-axis oscillation ismeasured using a z-axis encoder of a bond head assembly of a wirebonding machine.
 5. The method of claim 2 where the z-axis oscillationis measured in connection with an iterative process such that the z-axisforce profile determined for each of the bonding locations at step (a)results in an acceptable z-axis deflection profile for each of thebonding locations.
 6. The method of claim 5 where a maximum deflectionvalue included in the z-axis deflection profile is below a predeterminedthreshold.
 7. The method of claim 1 wherein the z-axis force profiledetermined in step (a) includes a profile corresponding to a portion ofa wire bonding cycle including lift off of a bonding tool after a wirebond is formed.
 8. The method of claim 1 wherein the z-axis forceprofile determined in step (a) includes a profile corresponding to aportion of a wire bonding cycle including initial impact of a free airball with a bonding location of the semiconductor device.
 9. A method ofdetermining a maximum bonded ball diameter, the method comprising thesteps of: (a) determining a maximum bond force for a bonding location onan unsupported portion of a semiconductor device for the formation ofwire bonds; (b) determining a z-axis constant velocity profile forformation of wire bonds at the bonding location; and (c) determining, ona computer, a maximum bonded ball size for the bonding location usingthe maximum bond force determined in step (a) and the z-axis constantvelocity profile in step (b).
 10. The method of claim 9 wherein thecomputer is a computer on a wire bonding machine.
 11. The method ofclaim 9 wherein step (c) includes using at least one data structureincluding values related to a maximum bonded ball size, along with themaximum bond force and the z-axis constant velocity profile, todetermine the maximum bonded ball size.
 12. A method of determiningbonding parameters to be applied to each a plurality of bondinglocations of a semiconductor device during a wire bonding operation, themethod comprising the steps of: (a) measuring z-axis deflection valuesat a plurality of bonding locations on an unsupported portion of atleast one reference semiconductor device at a plurality of bond forcevalues; and (b) determining bonding parameters for each of the bondinglocations using the z-axis deflection values measured during step (a),wherein the bonding parameters determined in step (b) includes at leastone of optimal damping gain, maximum die settle time, maximum safecontact velocity, and maximum safe bond force.
 13. The method of claim12 wherein the bonding parameters determined in step (b) includesoptimal damping gain.
 14. The method of claim 12 wherein the bondingparameters determined in step (b) includes maximum die settle time. 15.The method of claim 12 wherein steps (a) and (b) are performed usingfeedback and an iterative process.
 16. The method of claim 12 whereinthe bonding parameters determined in step (b) includes each of optimaldamping gain, maximum die settle time, maximum safe contact velocity,and maximum safe bond force.
 17. The method of claim 12 furthercomprising, before step (a), the step of providing a maximum z-axisdeflection value for the semiconductor device.
 18. The method of claim17 wherein the step of providing the maximum z-axis deflection valueincludes a user providing the maximum z-axis deflection value.
 19. Themethod of claim 17 wherein the step of providing the maximum z-axisdeflection value includes automatically determining the maximum z-axisdeflection value to be a value at which damage to the semiconductordevice does not result.
 20. The method of claim 12 wherein step (a)includes measuring the z-axis deflection values at the plurality ofbonding locations at unsupported portions of the at least one referencesemiconductor device.